1. Field of the Invention
This invention relates to an apparatus for shielding air from a path of molten metal in a laddle to a tundish in continuous casting facilities to prevent oxidation of the molten metal with a recognition of the fact that, in continuous casting facilities, molten metal in a laddle is poured, through a nozzle provided in the bottom wall of the laddle, into a tundish which is located beneath the nozzle and then into a casting mold and, at such time, it is necessary to prevent oxidation of the molten metal which would occur by contact with air between the laddle and tundish.
2. Description of the Prior Art
In order to prevent oxidation of molten metal, it has been the conventional practice to set a seal box on a tundish cover where utilizing a manner to circumvent the nozzle of a laddle in a laddle support structure without a laddle lift mechanism, injecting an inert gas into a gap space between the laddle nozzle and seal box to prevent contact with air of the effluent molten metal from the laddle. However, the seal provided by an apparatus of such an arrangement is incomplete, has only a small sealing effect, and requires a large quantity of inert gas to maintain an inert atmosphere in the gap space between the laddle and seal box, coupled with problems connected with safety of operations on the casting floor.
On the other hand a laddle support structure with a laddle lift mechanism is free of the above-mentioned problem of contact with air of the effluent molten metal, but instead has drawbacks such as complication in construction and an increase in production cost. Owing to wide use of laddle support structures without a laddle lift mechanism, there has been a strong demand for an apparatus capable of preventing oxidation of molten metal without the accompanying aforementioned drawbacks.